AbstractA well‐known analytical method for linear systems is that which employs the Laplace transformation. Such method is applicable to analytical nonlinear systems in various ways, as has already been reported [1, 2]. A problem in this method is calculation of the multidimensional inverse transformation, which is normally performed after reduction to one dimension. However, if higher‐order terms have to be taken into account, the amount of calculation for the reduction becomes excessive, so that manual calculation is impossible. Thus, in this report we propose to achieve the reduction operation by computer. Algorithms derived are practical for application to systems that consist of the sum and product of linear subsystems, cascade connection, and feedback. These are quite efficient algorithms, fully utilizing the system characteristics. We show that the advantage of the algorithm is to have the output in the form of frequency compone